In less than an hour, the two-week-old, miniature makeshift city was in ruins.
Scattered across the area were overturned tents, pillows, sleeping bags, yoga mats, tarps, backpacks, food wrappers and water bottles. Signs decrying corporations and police still hung from lampposts or lay on the ground.
Protesters had stayed awake through the night, waiting for the expected raid. Officers and sheriff's deputies from across the San Francisco Bay area surrounded the plaza in front of City Hall at around 5 a.m. and closed in. Eighty-five people were arrested, mostly on suspicion of misdemeanor unlawful assembly and illegal camping, police said.
Later Tuesday, hundreds of protesters gathered at a library and marched through downtown Oakland. They were met by police officers in riot gear, and several small skirmishes broke out.
The protesters eventually made their way back to City Hall as dusk approached.
"It's really, really tense and I think the cops are trying to walk a fine line, but I don't think they are going to back down and neither are the demonstrators," said Cat Brooks, an organizer. "We're on the move. For now."
No one was injured during the Tuesday morning raid, Interim Oakland Police Chief Howard Jordan said. The plaza was "contained" at around 5:30 a.m., city officials said.
By midmorning, city workers had started collecting the debris. Some would be held for protesters to reclaim, the rest would be thrown away, the city said.
The Oakland site was among numerous camps that have sprung up around the country, as protesters rally against what they see as corporate greed and a wide range of other economic issues. The protests have attracted a wide range of people, including college students looking for work and the homeless.
In Oakland, tensions between the city and protesters escalated last week as officials complained about what they described as deteriorating safety, sanitation and health issues at the site.
City officials had originally been supportive of protesters, with Oakland Mayor Jean Quan saying that sometimes "democracy is messy."
But the city later warned the protesters that they were breaking the law and couldn't stay in the encampment overnight. They cited concerns about rats, fire hazards, public urination and acts of violence at the site, which had grown to more than 150 tents and included areas for health care, child care and cooking.
"Many Oaklanders support the goals of the national Occupy Wall Street movement," Quan said in a statement on Tuesday. "However, over the last week it was apparent that neither the demonstrators nor the City could maintain safe or sanitary conditions or control the ongoing vandalism."
There were reports of a sex assault and a severe beating and fire and paramedics were denied access to the camp, according to city officials, who said they had also received numerous complaints of intimidating and threatening behavior.
Protesters disputed the city's claims about conditions at the camp. They said the protest was dominated by a spirit of cooperation that helped keep the site clean and allowed disputes to be resolved peacefully.
Lauren Richardson, a 24-year-old college student from Oakland, complained that the disheveled state of the camp following the police raid gave a false impression. She said volunteers collected garbage and recycling every six hours, that water was boiled before being used to wash dishes and that rats had infested the park long before the camp went up.
"It was very neat. It was very organized," Richardson said. Volunteers at the medical tent erected on the site said paramedics had not been kept away.
On Thursday, the city ordered the protesters to vacate, though they did not set a deadline. Protesters said the number of people at the camp had steadily dwindled since the city posted the letter, while those who remained understood they would likely face a confrontation with police.
Associated Press writer Terry Collins contributed to this report.